Shuzhen Zou

Large area growth of monolayer MoS2 film on quartz and its use as a saturable absorber in laser mode-locking

Monolayer MoS2 film on quartz was fabricated by a home-made three-temperature zone chemical vapor deposition method. The photo, AFM image, Raman spectroscopy and HRTEM image showed that high quality as-grown MoS2 film completely covered the whole quartz substrate of a few cm2. A Nd:YVO4 laser with mode-locking operation was obtained by using the monolayer MoS2 on quartz as the saturable absorber (SA). To the best of our knowledge, this is the first report on large-area growth of high quality monolayer MoS2 film on transparent quartz substrate, and the first time that the CVD MoS2 SA was used in mode-locked solid state lasers. Because of the large area, high transmission, low non-saturable loss and high optical damage threshold of this material, it is very suitable for application in mode-locked solid state lasers.

Buried tungsten silicide layer in silicon on insulator substrate by Smart-Cut®

A single-crystalline Si/SiO2/poly-WSix/Sub-Si structure has been successfully fabricated by a new method incorporating a standard smart-cut® technique and a high temperature reaction between tungsten and silicon. Annealing at 800–1100 °C does not only strengthen the bonding of the wafers but also induces solid phase reaction of deposited tungsten and silicon. A poly-crystalline WSix (1 < x < 2) layer with a tetragonal structure is formed below the buried oxide layer. Cross section images of TEM show three steep interfaces of the four layers. It is found that increasing the annealing temperature is in favour of decreasing the sheet resistance of tungsten silicide and improving the crystal quality of the top silicon layer. However, a spreading resistance profile measurement shows that annealing under high temperature (≥1000 °C) will induce diffusion of tungsten into the Si substrate which is confirmed by the EDX results and the reason is presented.

85-W Burst-Mode Pluse Fiber Amplifier Based on a Q-Switched Mode-Locked Laser With Output Energy 0.5 mJ per Burst

We report a compact 85-W burst-mode pulse fiber amplifier seeded by a Q-switched mode-locked laser at 1064 nm. At a repetition rate of 154 kHz, the pulse duration of the burst is 4 μs containing 280 of 20-ps pulses with temporal space of ~14 ns, and the total burst energy is about 552 μJ per pulse. The pulse number and the burst repetition frequency can be adjusted from 121 to 154 kHz through increasing the pump power of the seed laser. To the best of our knowledge, this is the first time to observe this type burst pulse amplifier based on the Q-switched mode-locked seed laser. No significant amplified spontaneous emission and stimulated Raman scattering were observed in our experiment when the output power is less than 85 W.

Taper Fused Fiber Bundle

The first experimental demonstration of a 1 × 4 all-fiber power splitter capable of high-power operation is presented. The splitter, prepared by fused taper technique and fusion splicing technique, consists of one input fiber with a core diameter of 400 μm (NACORE = 0.22) and four output fibers with a core diameter of 200 μm (NACORE = 0.22). The device was tested at a laser power up to 166 W and it achieves a low excess loss of 0.56 dB and an excellent uniformity of less than 0.3 dB in port-to-port power splitting ratio. The results of theoretical simulation by the 3-D beam propagation method show that the performance of this splitter could be optimized further through modifying structure parameters.

1\times 4

We demonstrate a high-power blue diode laser operated at 447 nm combining laser diodes using an optical fiber bundle. As many as 127 diode lasers at 447 nm were coupled into 400 μ m/0.22NA fibers using an aspherical lens group with different focus lengths. The bare fibers were mechanically bundled through high temperature ultraviolet adhesive after the coatings of the 127 fibers were stripped. The diameter of the fiber bundle was 6 mm. The total output power of such a bundle was 152 W with electro-optical conversion efficiency of 27.56% and the RMS power instability was less than ± 1% within 3 h.

Coupler for High Power Splitting

The film properties and microstructures of (bottom)Si/SiO2/Ti(top) and (bottom)Si/SiO2/Ti/TiN/AlCu(top) stacks deposited by different processes were characterized. The resistivities of thin Ti films and the reflectivities of AlCu alloy films were found to correlate with the microstructure as well as the mean time to failure (MTTF) in the electromigration (EM) test. A quick-turn monitor for AlCu interconnect reliability in the semiconductor manufacturing industry was established.